Carburetor



R. ABELL CARBURETOR Dec. 23, 1947.`

Origal Filed Dec, 7, 1940 2 Sheets-Sheet 2 M CLICK I .r ZwmO M901 dun.@mit .momrh rwno no1 mwa @mii Patented Dec. 23, 1947 UNITED STATESPATENTl OFFICE CARBURETOR Rollin Abell, Fort Lauderdale, Fla. Originalapplication December 7, 1940, Serial No. 369,068. Divided and thisapplication January 9, 1945, Serial No. 571,983

16 Claims. 1

This invention relates to improvements in carburetors. 4

The invention provides apparatus by which the carburetor maintains asubstantially constant vacuum in its mixing chamber. And it alsoprovides for automatically changing the metering of fuel to maintain orto change richness of the mixture fed to the engine according to what isneeded for the exigencias of driving; as for example, for starting, orfor accelerating, or for merely maintaining speed, high or loW, at lightor heavy load.

The term constant vacuum as used herein relates to the strength ofvacuum in the mixing chamber; i. e. the degree of depression there belowsurrounding air. It signifies a strength which is continuouslysuiiicient, at least, to overcome whatever resistance may have to beovercome, in order to maintain continuity of fuel feed to the engine, inthe particular car in which the apparatus is to be installed. Preferablyit is also constant in the sense of being always below a predeterminedupper limit. For illustration, I consider the vacuum constant when itstays always within the low range of one or two inches of mercury, orwithin some other predetermined narrow range. In the particularapparatus herein pictured, I found the vacuum to remain at 1.5 inches Hgthroughout all reasonable speeds, grades and loads, this vacuum beingobserved at all speeds between and 80 miles per hour, and beingsuflicient, to draw from a local bowl. The constancy permits of thisvacuum being also applied to important uses outside of the carburetor,as, for steady wind shield wiping, and for lifting of fuel to thevicinity of the carburetor from a low rear reservoir, a boosting deviceof known type being used if requisite. When applied to fuel-lifting, theconstancy of vacuum strength maintains continuity of fuel flow; and,conversely, the continuity of fuel flow, under all conditions ofdriving, maintains the constancy of vacuum.

When speed or load increases, more fuel must be sucked in by theunchanged low vacuum. The apparatus automatically takes account of theseneeds and regulates the meter, as changes of load are indicated by theoperators changing the position of the throttle pedal, and as changes ofspeed are indicated by movements of the air valve. I have discoveredthat optimum relations exist when a turning of the throttle-valve movesthe straight taper meter about one quarter as far as is produced by anequal angular movement of the air valve; and that preferably this ratioof throttle effect to air valve effect is not more than 1:2.

This valvular control of mixture ratio of fuel and air renders theservice that has heretofore been performed by the customary choke; andno choke is requisite. Also it renders the service of the hithertocustomary accelerator pump; and no such pump is desirable. This isespecially so since the valve-control-of-meter tends to makeacceleration be at a more nearly uniform rate, with economy of fuel. Thecurrently felt need for fast idling is eliminated. By the application ofa thermostatic positioning control to the needle or the fuel jet, therichness of mixture is made appropriate for cold starting, and no chokeis requisite for this.

It is a feature that the whole apparatus improves over currently knowntypes of carburetors, in that it occupies little space, has simpleconstruction, few parts and low cost; and yet attains the constancy ofvacuum and mixture control as described.

It is an important practical object of the in-y vention to provide theapparatus in form available for quantity production; and also to embodythese numerous advantages in apparatus of satisfactory reliability inaction.

Other details of construction, and other advantages in construction andin operation, will appear from the description which follows and fromthe showing in the accompanying drawings.

The present application is a continuation in part of my application forpatent, Serial 212,568, led June 8, 1938; also is a continuation in partof my application for patent Serial 248,072, filed December 28, 1938,and it is a division of my application for patent Serial 369,068, filedDecember 7, 1940, entitled Apparatus for feeding and metering liquidfuel to an internal combustion engine.

In the accompanying drawings:

Figure l is a side elevation of apparatus embodying the inventionincluding in vertical medial section a local iloat chamber and liftingapparatus operated by the carburetor vacuum for supplying fuel to thecarburetor;

Figure 2 is an elevation looking from the right at the carburetorportion of Figure 1, the float chamber and the carburetor bowl beingomitted, and a portion being broken away to show the metering pin;

Figure 3 is an elevation, in medial section of Figure 2;

Figure 4 is a plan, in section on 4-4 of Figure 2;

Figure 5 is a plan, in section on 5-5 of Figure 3; but showing thesliding jet and needle sleeve unsectioned. i

Figure `6 is a side elevation of another structural embodiment of thefeature of the invention which provides a constant vacuum and controlledproportion of mixture;

Figure '7 is a medial vertical section through the carburetor of Figures1, 2, 3 and 6, showing the air valves partly open;

Figure 8 is a similar view with the air valves fully open;

Figure 9 is a diagrammatic chart of the relation of the constant vacuumof the invention to the vacuum produced at various speeds in a .plaintube carburetor of prior art; and

Figure 10 is a diagrammatic chart of changes in mechanical and airfriction resistance to which the air valve is subject at various speeds,and their cooperation to maintain the vacuum constant, as speedsincrease.

The drawings illustrate a carburetor with which I have attained theimportant results herein set forth, in operation of a Ford V8-.cylindercar kof 1938, with gasoline. Other volatile fuels can be used,appropriate adjustments of design being made.

The carburetor represented is of a preferred simple construction formaintaining a constancy of vacuum which feeds and mixes fuel with air-in a degree of richness which is automatically varied, for dealing withthe exigencies of car driving, to accord with the fuel ratio needed`l'or optimum results, either for economy of fuel or for power of drive.The construction shown can be produced economically in quantity methods,one important feature being that it permits the -use of a straight taperjet 'meter (H9, Figure 2) connected to the valves (|02, |03; |26, Figure3) so that it can make a relatively lean mixture for operating at partthrottle, without excluding the ability to produce full power at widethrottle. Thus it economizes fuel during ordinary driving; and yet makesmaximum acceleration available, without fuel waste.

As seen in Figures 3, '7, 8, the carburetor is a round tubular bodywhich is set vertically for down draft of air, and has its mixingchamber |25' between the inlet air valve vanes |03 and the outletthrottle valve disk |20. The air valve consists of two segmental vanes,whose hubs 4cross the middle of the casing diametrically on parallelpivot shafts |02; and whose perimeter arcs each seat against the tubewall obliquely at about 60 from the axis. Above these hubs a 'frame |00,inserted at the air entrance of the tube, has a depending diametricalcross bar l0? with curved under surface to rest on top surfaces of theVane-hubs, against which it is pressed continuously by tensile springs|04 that are anchored to this frame |00, and are attached to the vanes|03, tending to draw the vanes up against their respective seats,initially vhaving stress that is Aabout half of what they have when theair Valve is wide open. Thus they provide initial vacuum; and at al1times their downward pressing of bar |01 against the hubs of the vanesprovides friction which prevents flutter of the vanes, being a brakeshoe and air seal between them,

The spring |04 of each air vane is dimensioned and mounted so that, asit elongates and increases in tension, with the opening of the airvalve, its end on the vane swings with'the vane, `about the axis of thevane, so as to make the axis of the spring approach the axis about whichthe vane is turning; and thus the arm of that lmoment which is tendingto close the valve, be-

comes shortened as the magnitude of "the force of that moment grows withthe extension of the spring.

But for making the vacuum be constant, the factors concerned can becombined variously. The preferred construction is illustrated in Figures3-8, which indicate a combination with practically no change of airfriction and practically no change of the moment of mechanicalresistance.

The air valve in the illustrative embodiment which is being describedhas to do work when it moves; and it should be responsive to minutechanges. This is important, for if the valve were to -stick at low speedthe engine would stop, When idling, the air opening may be not over .005inch. I vhave found that by making each air vane completely unbalanced,i. e., with the air which can impinge on it passing wholly on one sideof its pivot, the valve provides suflicient torque to overcome thefriction of its shaft |02, as well as the drag of the brake surface |01that prevents valve flutter, and to propel the fuel meter. The gearingof the two vanes together at |02', Figure 4, makes all of the torquefrom both vanes be available and sufficient for these services. Bymaking the air Valve in two vanes, instead of one large one, simplicityof structure is achieved, with diametric pivots, and a good structurefor mixing.

The springs |04 used in the installation that is being described eachhave free length of onehalf inch of coil, with 25 convolutions of .020wire. When set, the Vcoils are stretched to one inch for theclosed-valve initial position; and, when 'suction of the engine begins,this produces the vacuum of 11/2 inches Hg. When the valve has moved 60to wide open position the spring coil is stretched to one and one halfinches, and has twice its initial tension; the 60 swing has reduced theeffective leverage through the arm about the shaft |02 from one-halfinch to onefourth inch, and the moment mechanically opposing the openingof the valve is the same as it was at the start. Thus the torque set upcn the air valve shaft is the same at both extremes of valve travel.

The constant vacuum thus provided in the mixing chamber |25' draws infuel which reaches the spray tube |25 (Figures 3, 5) from any suitablesupply duct |24, |25 (Figure 2) through aA metering passage between atube ||8 and a straight-tapered metering needle ||9 whose longitudinalposition in the tube I8 is fundamentally set by an atmospherictemperature thermostat |36, and is operatively under control of the airvalve and throttle valve |03, |20 through their shafts |02, |21 andconnections, which, in Figure 2, comprise crank arms |30, |32; links|3|, |33; and a lever |34 whose mid-portion is pivoted on one end ofthat tube ||8 and can move the tube longitudinally in its housing on theoutside of the carburetor body.

Figure 2 illustrates an arrangement in which the fuel metering pin ||9has a slide bearing in an end part of the tube |8, and a taperingportion within ther tube. The end of this pin outside of the tube isattached to the thermostat |38 which is a sheaf of five bi-metallicleaves clamped together, the second and fourth leaves being cut short at|38 to make the end portion of the sheaf have flexibility, so that itcan bend without making the pin bind in .its close t in its tube H8.

The middle of the body of the tube has passages and ports for fuel topass transversely at a rate which depends upon what part of the straighttaper of the pin is opposite the metering port.

Suction in the mixing chamber |25' draws fuel from an adjacent supplychamber ||3, which in Figure 1 is behind the fuel lifting chamber ||2,through a duct |32 (dotted in Figure 1) that leads it to the valveintake |24 (Figure 2), Where its rate of entering the duct |25 iscontrolled by the measure of space currently existing between thefuel-metering valve-element, comprising the needle or pin I I3 and itsseat in the jet tube |8. This regulatory valve is not located within themixing chamber as is usual; but its outlet duct |25 leads thither by anyconvenient course and has there a discharge orifice construction thatextends completely across the mixing chamber |25'. This end portion ofthe duct |25 is a tube which has its end closed, is set horizontal, andhas discharge orices |08 distributed on all sides of the tube atintervals across the whole width of the chamber, between air andthrottle valves.

The metering pin I9 represented in Figures 2 and 6 is made with a taperthat is long and straight. This favors low cost, and high precision, inproduction of valve-elements by mass manufacture methods, and permitsprecision in setting the rate of fuel flow, under regulatory control bymovements of air and throttle valves. The illustrative pins use aboutve-eighths inch length of straight taper, in a taper-ratio of about l in30.

'I'he local chamber for supply of fuel to the inlet duct 02 may besituated in any convenient place; and its contents may be replenished toconstant level by any suitable means. In the structure here beingdescribed, fuel contents are maintained at constant level by power ofthe constant vacuum in the carburetor mixing chamber |25' which has asmall suction air duct ||0, Figure 1, through a Venturi vacuum booster||4, and valve 49 actuated by the float 45. This part of the apparatushere shown is not claimed herein, but is described and separatelyclaimed in my said Letters Patent 2,304,066 of December 8, 1942.Pulsations of vacuum in chamber ||2, alternating with pulsations ofatmosphere, with the falling and rising of the float 45 at an averagefrequency of 60 or so` per minute, cause rapid repetition of surges ofliquid fuel in the chamber ||2 to a hydrostatic head suflicient toreplenish the bowl, lifting this fuel from a distant low reservoir 00through inlet 0| into the local chamber |l2, whence it iiows into theatmospheric bowl as needed. The described means for producing constancyin the strength of vacuum can be designed so that the vacuum will alwaysbe sufficient to lift the fuel to a level which is constant, relative tothe carburetor, under all conditions of throttle opening in normaloperation of a car.

The invention provides for differential regulatory control of themetering of fuel by the air valve shaft |02 and the throttle valve shaft|21. The swing of the air valve crank |30 on shaft |02, and the travelof its link 3| connected to one end of the lever |34', approximateparallelism with the swing of the throttle valve crank |32 on shaft |21and the travel of its link |33 which is connected to the other end ofthat lever |34. The movements of these said parts are in approximateparallelism with the straight endwise travel of the elements |8, ||9 ofthe fuel meter, one of which elements is pivnted on the lever |34'between the said two ends of that lever. The degree of opening betweenthese meter elements H8, H9, at any instant is a resultant of thepositions occupied at the same instant by the two valve cranks |30, |32.Whenever either the air valve or the throttle valve moves, it moves itsown end of the lever, and thus moves the meter element H8proportionately, but does not move the valve which is connected at theother end of the lever. Since that other valve may occupy any of variouspositions,

and may itself be in motion at the very same instant, there may be agreat complexity of lever positions and angles. Assuming that the valvesand meter have a certain zero position, as when the engine is idling,and neither the air valve nor the throttle valve is perceptibly open,one may observe that when acceleration is desired the drivers moving ofthe throttle and its crank arm |32 to a moderately open position shiftsthe lever |34' and the meter element ||8 to a slightly open position-before the air valve is moved. This enriches the mixture, say to aratio of 13 or 14 of air to one of fuel vapor, and produces maximumacceleration. The increase of suction which attends rising engine speedopens the air valve |03 and so shifts the meter, accumulatively, to alarger opening which maintains and even increases the richness ratiowhile drawing in more of both fuel and air. But when the desired speedhas been reached, the drivers relaxing of the throttle, to ceaseacceleration, lets the richness ratio fall back somewhat, to theeconomical ratio 16 to 1, leaving the air and throttle valves bothstanding at whatever positions occur while maintaining the higher speed.If the throttle be afterward merely to call for more power, withoutincrease of speed, as on reaching a more diiiicult grade, the operatorscontinuation of throttle opening pressure continues the needed richnessof mixture. He can set the throttle Valve open Wide, advancing themetering pin accordingly for accelerating by enrichment. But, with anyensuing increase of engine speed, the resulting wider opening of airvalve restores the predetermined economical ratio of mixture, at thesame time advancing the metering pin still further, which provides thegreater feeding of fuel that is needed for top speed.

In the above described connections of throttle and airvalves to fuelvalve, and in all alternative arrangements, opening movements of thethrottle valve and air valve voperate accumulatively to open, andconversely their closings have cumulative effect toward closing, thefuel valve.

My differential control of the richness of the mixture permits of havingthe necessary rich ratio, 12 or 13 of air to 1 of fuel, duringacceleration; and yet operating at the economical ratio 15 or 16 to 1for ordinary constant speed. The parts can be organized so as to operateat Whatever mixture is desired as the economical normal running mixture.

The relative lengths of the crank arms |30 and |32 and of the lever armsmay be selected so as to produce whatever leverage ratio may be desired,between the valves and the meter. This ratio may differ for differentfuels, and for different elevations. Also the ratio between the airvalve and the throttle valve, as to the distance each will move themeter during an equal angular travel of valve, is subject to variationat choice. I have discovered and have demonstrated by analyses ofexhaust gases that in a carburetor of the type herein described theoptimum ratio, for gasoline fuel used at sea level, has the throttlemove. the fuel valve only about. one-.fourth .as much es` the air valvemoves the fuel valve element in an equal angular movement of air valve.The. dotted lines in Figure 6 express this ratio approximately, theleverage shown in full lines being ignored when this dotted feature isconsidered.

I have found the important fact that by providing a ratio of one to fourthe various influences can be integrated, with high .eciency andeconomy, for maintaining performance as above described, yet. with therebeing always available an automatic. change to a richer ratio when morepower is demanded, by a mere pressure .of the driver .on the throttle.However, results that are good can be had up to a critical ratio inwhich the `air valve moves .a fuel valve element twice as far as thethrottle valve moves the fuel valve element to which it is connected inan opening movement of equal angular distance.

The meter element and mid-portion of the lever 434' are responsive tomovement of each valve, as thus described, because the meter is easilymobile while each valve is so iirmly held between its spring and theopposing pressure of air or vot .the operator, as the case may be, thatit stands iirm in whatever position they x it, and s acts as a fulcrumwhenever the other valve moves.

The vjoint and :differential control of metering ,iet may be had bygearing which -does not include a lever. One such means is by connectingone of the valves to the jet, and the other to the pin, as seen inFig-ure 6, through crank arms whose llengths are in desired ratio. Inthis vcase the metering` pin H9 is moved by link |33 and .a reductiongearing |32 connection of the throttle valve |27, while the farm 130'0.1 the air 4valve is `directly connected to the jet H8 `through a link13:1. rThe opening travels of the two valves move the needle and the jetin opposite directions.

The delivery of fuel into the mixing chamber A|25' in Figures 2-:8 isthrough a spray tube |25 which .is set across. the air passage and hasthe two characteristics which cooperate 'to produce :a homogeneousmixture, i'li'st that the discharge occurs from holes at numerouslocations on the way across the air stream (Figure and second that .thespray streams `originate in and vproceed in .numerous directions from asheltered region f (Figures 7, 8)., in the midst of the air stream fordispersion with a minimum of coalescing. When using gasoline as fuel Ihave lfound 'that surface tension of the liquid alfords such resistancetoits passing through l'these holes that it iows to the end of the tube,and escapes in nely divided state with uniformity -of Volume in allpartsof the length, even though the holes are as large as 1%" indiameter.

The `setting .of the air vanes 103 on parallel pivots 1.02 that .crossthe middle of a vertical, down-draft, round air passage |07! (Figures 3,4) makes each valve be. segmental, vwith its pivot .at its chord and beexposed to :air pressure on only one side yoi its pivot. edge of thevane is round, and opens away from a round wall, the whole extent of thehalf -round edge. vstands 'at least slightly away from the wall wheneverthe vane is at vall open. Therefore, whenever the engine `is vrunningYthere is always a current .of air between the wall and all parts ofthat edge :of the vane which is adjacent to the wall. This avoids'trouble Afrom frost. and' icelock..

Bjrfmakingxthe `closedfpositionlbe at an angle Since vthe moving belowhorizontal, the rather abrupt path of departure of the vane from thevertical walll makes the air valve be wide open, with the vane verticalat the middle, within a swing of only or so. This occurs at high speedsand helps to keep the Vvacuum down, within the required range. For.control of vacuum at low speeds, the taper of the passage wall from airvalve to throttle valve begins in near perpendicularity to the plane olithe seated air valve. Therefore whenever the air valve is barely openthe air passage is very narrow, with consequent retardation of airinflow, which helps to raise the vacuum to the desired range ofconstancy. From the said perpendicularity the taper proceeds into acurve that is convex toward the path which the edge of the swinging vanefollows in its more open positions (Figures 7, 8). Factors that combineat vlow speed to produce the desired 11/2 Hg inches oi vacuum includetheinitial tension of the spring HM. and the air retardation abovedescribed. At great lspeeds factors that combine to prevent the vacuumrising above the desired range of constancy include the shortening ofthe efiective length of the arm of the spring, the widening of thel airpassage, and its straightening from initial crookedness. The factorsconcerned can be Varied in a mutually compensatory manner to produce avacuum that is constantly within the range of one to two inches ofmercury, or other desired range, at all stages of air valve opening,corresponding to all speeds and loads.

vFigure 10 is a chart indicating how the simultaneous increasing of airfriction and diminishing of forcesv tending to hold the valve closed aremutually Abalanced so that neither the increase of the one. nor the.diminution of the other takes the vacuum out of the said range. Figure9 con- .trasts the constant vacuum thus obtained with the vacuum whichcarburetors of the plain tube type experience, in which the vacuumincreases with the square of the speed of the inrush of air. The lattervacuum rises along the curved line up to nearly five inches Hg during arise of speed of car from Zero to miles per hour. But in the `carburetorYof the invention, the curve marked constant vacuum is constantly withinthe range of 1 to. 2 inches, illustrated as being constant at 1.5.inches Hg.

As .the vacuum vof a mixing chamber can be used exteriorly, and can beboosted by Vknown methods, the constancy of the carburetor vacuum is .afeature of importance for steady and sure operation oi the outsideutility to which it may be applied, which, lfor example, may be theoperating of a windshield wiper. The chart Figure 9 thereforeillustratively shows a boosted constant vacuum of ll to V6 inches; andFigure 1 illustrates the use of such a boosted constant vacuum forraising fuel unfailingly from a low level reservoir -0U through duct 0|to pump chamber 1l t2. Vacuum reaches the valve 49 through a Venturibooster H from an external orifice IIU of a duct (not shown) kfrom amixing chamber The combined eiect of the constant vacuum and .theillustrated ratio of Valves, meter, and `leverage connection produces aneconomical firing mixture having about 1 part of fuel vapor to 16 ofair, when the ratio is such that the air 'valve moves Athe meter fourtimes. as far as the Ithrottle valve moves the same in an equal angulartravel of Yvalve. In :operation the valves enrich this mixtureautomatically and temporarily from time to time, 'up to about 1 to 12for full power.

While the ratio between valves and meter is a matter of choice, mydiscovery that a 4:1 movement of meter is best for all speeds and loadshas been confirmed by exhaust gas analyses. If the gearing ratio is madeless than 2:1 the mixture becomes too rich in acceleration and inclimbing hills at moderate speed, so that a ratio lower than that is notadvisable.

The connecting of air valve and throttle valve to the metering means maybe in any of several ways. Figure 2 shows valves both connected to anelement that moves the tube of the meter with respect to a stationarypin. Obviously the element might be arranged to move the pin, relativeto a stationary tube. In Figure 6 one valve moves the tube and the othervalve moves the pin. There may be two metering tapers on a single pin.In another good arrangement (not shown) the two tapers may be onseparate metering pins, one pin worked by the air valve and the otherpin worked independently by the throttle valve, but both jets feedingthe same vacuum chamber. The leverage ratios of the respective Valvecon- -nections to the meter will differ from each other according to theprinciple above set forth, the parts being arranged so that the fuelmetered by the throttle valve is about one fourth as much so thatmetered by the air valve, thus maintaining the principles ofdifferential metering.

I claim as my invention:

1. A carburetor comprising a body having a mixture passage extendingtherethrough; a manually controlled throttle valve in the outlet,comprising a disk on a pivot shaft; at least one air valve in the inlet,comprising a vane on one side of a second pivot shaft, openable by airpressure thereon; a spring attached to the vane and body, tending toclose the vane; a fuel supply chamber and a duct therefrom having adischarge orifice in the mixture passage intermediate the Vane andthrottle; and a fuel valve in said duct comprising relativelyreciprocable tapered pin and seat elements; combined with a crank arm onthe said throttle shaft; a crank arm on the said vane shaft; a leverpivoted on one of said valve elements and having oppositely extendingarms; a link connecting the throttle crank arm to one of said leverarms; and a link connecting the air vane crank arm to the other leverarm; the lengths of said lever arms and crank arms being so proportionedthat a given angular movement of the vane arm by air pressure on thevane shifts the fuel valve element accumulatively with, and at leasttwice as far as, an equal angular movement of the throttle arm.

2. A carbureter comprising a body having a mixture passage extendingtherethrough; a manually controlled throttle valve in the outlet,comprising a, disk on a pivot shaft; at least one air valve in theinlet, ycomprising a vane on one side of a second pivot shaft, openableby air pressure thereon; a spring attached to the vane and body, tendingto close the vane; a fuel supply direction for further opening as airpressure opens the vane; the lengths of crank arms and of the saidlinkage connections being so proportioned that a given angular movementof the vane by air pressure thereon shifts its fuel valve element atleast twice as far as an equal angular movement of the throttle crankshifts the valve element to which the throttle is connected.

3. A carburetor comprising a body having a mixture passage extendingtherethrough, a manually controlled throttle valve in the outlet,comprising a disk 0n a pivot shaft; at least one air valve in the inlet,comprising a vane on one side of a second pivot shaft, openable by airpressure thereon; a spring attached to the vane and body, tending toclose the vane; a, fuel supply chamber and a duct therefrom having adischarge orifice in the mixture passage intermediate the vane andthrottle;` and a fuel valve in said duct comprising relativelyreciprocable tapered pin and seat elements; combined with a crank arm onthe said throttle shaft; a crank arm on the said vane shaft; linkageconnecting the throttle crank to one of said valve elements; and linkageconnecting the vane crank to one of said valve elements; said crank armsand their said connections being so arranged that a movement of the airvane opens or closes the fuel valve cumulatively with an opening orclosing, respectively, of the throttle valve, and proportioned so that agiven angular movement of the air vane makes chamber and a ducttherefrom having a discharge orifice in the mixture passage intermediatethe vane and throttle; and a fuel valve in said duct comprisingrelatively reciprocable tapered pin and seat elements; combined with a,crank arm on the said throttle shaft; a crank arm on the said vaneshaft; linkage connecting the throttle crank to one of said valveelements for shifting that element in opening direction as the throttleis manually opened; linkage connecting the air vane crank to the othersaid valve element` for shifting that other element in the opposite atleast twice as great a shift of the fuel valve as an equal movement ofthe throttle valve.

4. A carburetor as in claim 3, wherein the said crank arms and theirlinkage connections are So proportioned that a given opening movement ofthe air vane opens the fuel valve approximately four times as far as anequal angular movement of the throttle valve opens the fuel valve.

5. A carburetor as in claim 3, further characterized in 'that athermostat, based on the said body, has its moving end secured to one ofthe said fuel valve elements, thereby to modify, according toatmospheric temperature, the starting position of thefuel Valve, and itsareas of opening produced by the throttle and vane.

6. A carburetor as in claim 3, further characterized in that the saidspring is a tension spring attached to the vane for its direction ofpull on the vane to shift toward the vanes pivot shaft as the vaneswings open, thereby t0 maintain its effective vane-closing momentapproximately constant and tending to maintain a constant strength ofsuction in the chamber between vane and throttle.

7. A carburetor comprising, in combination, a body having a mixturepassage extending therethrough; a manually controlled throttle valve inthe outlet;` at least one air valve in the inlet, comprising a vanepivoted on an axis at one edge of the vane, openable by air pressure,and having a spring attached to the vane and to the body in tensiontending to'close the Vane; that part of said passage which is betweenthese valves being a vacuum and mixing chamber, the said spring beingmounted on said vane andV body for the line of its pull on the vane toshift toward the axis of the vane as the vane swings open, to reduce thelength of its arm effective for closing the vane in a ratio thatmaintains the vane-closing moment approximately constant and so tends tomaintain a constancy of strength of vacuum in the said vacuum chamber;combined with a liquid fuel supply chamber outside of the said passageand adjacent tc the vacuum and mixing chamber, a duct for liquid fuelleading from said fuel supply chamber int-o said vacuum and `mixingchamber; ,a fuel regulatory valve comprising two relatively movableelements for said duct, and transmission mechanism connecting said vaneshaft to one of sai-d elements, and transmission mechanism connectingsaid throttle shaft to one of said elements, each mechanism shifting theelement connected therewith to regulate the area of valve opening, saidmechanisms being effective separately and cumulatively and proportionedfor a given angular movement of the vane to change the fuel valveopening at least twice as much as an equal angular movement of thethrottle.

8. A carburetor comprising, in combination, a body having a mixturepassage extending therethrough; a manually controlled throttle valve inthe outlet; at least one air valve in the inlet, comprising a vanepivoted on an axis at one edge of the vane, openable by air pressure,and having a spring attached to the vane and to the body in tensiontending to close the vane; that part of said passage which is betweenthese valves being a vacuum and mixing chamber, the portion of saidpassage which is closed by said inlet vane having a segmentalcross-section, and the said vane therein being segmental, the vanes saidpivotal axis being at its chordal edge, from which the vane extendsacross the passage and has its curved edge seating against the arcuatewall of the said segmental cross-section; said spring being mounted onsaid vane and body for its line of pull on the vane to shift toward thepivotal axis of the vane as the vane swings open, to reduce the lengthof its arm elfective for closing the vane in a ratio that maintains thevane-closing moment approximately constant and so tends to maintain aconstancy of strength of vacuum in the said vacuum chamber; combinedwith a liquid fuel supply chamber outside of the said passage andadiaoent to the vacuum and mixing chamber, a duct for liquid fuelleading from said fuel supply chamber into said vacuum and mixingchamber; a fuel regulatory valvey comprising two relatively movableelements for said duct, and transmission mechanism connecting said vaneshaft to one of said elements, andy transmission mechanism connectingsaid throttle shaft to one of said elements, each mechanism shifting theelement connected therewith to regulate the area of valve opening, saidmechanisms being effective separately and cumulatively and proportionedfor a given angular movement of the vane to change the fuel valveopening at least twice as much as an equal angular movement of thethrottle.

9.r A carburetor as in claimk 7, in which there are two said, chambersfor holding fuel supply, outside of the said passage and adjacent to thevacuum and mixingv chamber, that one of these two supply chambers whichis first. in the line of supply having an inlet fory liquid fuel fromvbelow and an outlet for liquid to flow by gravity to the supply chamberwhich. is second in line of supply, said first chamber also having, forair, a port with valve for inlet from atmosphere, and an out- -let portwith duct and valve for air to go from it to said vacuum chamber,A witha float for openingthe said ports alternately; the said fuel ductleadingy from said second. fuelr supply chamber; whereby at all speedsandA loads the said constant strength of vacuumv can feed fuel to themixing chamber from a reservoir at lower level.

10. A carburetor as Iin. claimv 7 in which there is also a duct leadingto said vacuumllamben having an inlet orifice located at the exterior ofthe body and adapted for connection to an air operated mechanism outsideof the mixing chamber, whereby the approximately constant vacuum of saidv-acuum and mixing chamber can exert approximately constant power tooperate apparatus having moving elements.

l1. A carburetor as in claim 7, further fcharacterized in that the saidregulatory valve in the fuel duct is outside of the vacuum and mixingchamber; and that the fuel duct has a terminal portion comprising a tubeset horizontally across the said passage between the inlet valve and thethrottle valve; with discharge orifices on all sides of said tube atintervals all of the way across the said constant vacuum space.

12. A carburetor as in claim 8, further characterized in that the saidinlet portion of the passage has a round cross-section, and that thereare two 0f the said segmental vanes therein, having their chordal edgespivoted across the middle of the passage, said vanes extending obliquelythence and their curved edges seating against opposite walls of thepassage; the structure and mounting of the said tension springs of eachvane being such that when the vane is fully open each spring has tensionof about double and has a moment arm of about half what the tension andmoment arm respectively are when the vane .is seated. f

13. A carburetor as in claim 8, further characterized in that the saidinlet portion of the passage has a round cross-section, and there aretwo of the said segmental vanes therein, their chordal edges beingpivoted across the middle of the passage and geared together; and theircurved edges seating obliquely against opposite walls thereof; hubs atthe pivotal axes, and a friction anti-flutter brake pressing on thehubs.

14. A carburetor as in claim 8, further characterized in that the saidinlet portion of the passage has a round cross-section, and there aretwo of the said segmental vanes therein, their chordal edges beingpivoted across the middle of the passage, and geared together; theircurved edges seating obliquely against opposite walls thereof; hubs atthe pivotal axes; a frame loose in the inlet, having a shoe resting onthe hubs, covering the space between the hubs against air leakage; thesaid tension springs of the vanes being attached to the body throughthis frame, whereby their spring pressure on the hubs providesvanti-flutter braking,

15. A carburetor as in claim 8, further characterized in that the saidinlet portion of the passage has a round cross-section, and there aretwo of the said segmental vanes therein, having their chordal edgespivoted across the middle of the passage; these vanes extendingobliquely across the passage and seating their curved edges againstopposite walls; further characterized in that the longitudinal contourof that part of the passage wall that is beside the paths of the edgesof the vanes is convex toward the middle of the passage; whereby, duringair valve opening travel, the course opened for air travel is initiallytortuous and narrower than the instant measure of valve travel, thusaugmenting air friction at this stage of opening, with diminution oftortuosity as opening travel proceeds.

16. A carburetor as in claim 8, further characterized in that the saidinlet portion of the passage has a round cross-section, and there aretwo of the said segmental vanes therein, pivoted across the middle ofthe passage at their chordal 13 edges, and extending thence to oppositeWalls; further characterized in that the delivery end of said fuel ductis a tube extending fully across the vacuum and. mixing chamber, sethorizontal, adjacent to and parallel to said chordal edges in the middlespace sheltered thereby; there being discharge orifices on all sides ofthis tube, distributed along it all of the Way across, for induction offuel to all parts of the space which is ben tween the inlet vanes andthe throttle Valve.

ROLLIN ABELL.

REFERENCES CITED The following references are of record in the le ofthis patent:

Number Number UNITED STATES PATENTS Name Date Funderburk Oct. 23, 1934Reichenbach Jan. 22, 1918 McCarthy June 14, 1921 Mock June 1, 1926 GouldNov. 27, 1934 Hartwell Dec. 21, 1926 Kerns Dec. 17, 1918 FOREIGN PATENTSCountry Date Great Britain May 13, 1912 Great Britain July 16, 1935

